Name | Hardness | Specific Gravity | Structure | Refractive Index | Birefringence | Plechorism | Fluorescence |
Agate (Quartz) | 6.5+ | 2.60-2.65 | Hexagonal | 1.54-1.55 | up to +0.006 | None | Variable |
Alabaster | 2+ | 2.30-2.33 | Microcrystaline | 1.520-1.530 | 0.01 | ||
Alexandrite | 8.5 | 3.70-3.73 | Orthorhombic | 1.744-1.755 | 0.011 | v Weak | None |
Almandine Garnet | 7.5 | 3.95-4.20 | Isometric | 1.78-1.81 | None | None | None |
Amazonite | 6+ | 2.56-2.58 | Triclinic | 1.522-1.530 | -0.008 | None | Weak |
Amber | 2to3 | 1.05-1.30 | Amorphous | 1.54 | None | None | Variable |
Amblygonite | 6 | 3.01-3.03 | Triclinic | 1.611-1.637 | 0.026 | None | v Weak |
Amethyst Quartz | 7 | 2.63-2.65 | Hexagonal | 1.544-1.553 | 0.009 | v Weak | Weak |
Anatase | 5.5+ | 3.82-3.95 | |||||
Andalusite | 7.5 | 3.12-3.18 | Orthorhombic | 1.641-1.648 | -0.007 | Strong | Weak |
Andradite Garnet | 7+ | 3.60-3.68 | Isometric | 1.738-1.745 | None | None | None |
Anhydrite | 3+ | 2.90-2.99 | Orthorhombic | ||||
Apatite | 5 | 3.17-3.23 | Hexagonal | 1.632-1.646 | -0.002 -0.004 | Weak to v Strong | Variable |
Apophylite Fish-eye | 4.5+ | 2.30-2.50 | Tetragonal | ||||
Aquamarine | 7.5+ | 2.67-2.71 | Hexagonal | 1.577-1.583 | -0.006 | Definite | None |
Aragonite Tufa Travertine | 3.5+ | 2.94 | 1.530-1.685 | -0.155 | |||
Augelite | 5 | 2.7 | |||||
Aventurine Feldspar | 6+ | 2.62-2.65 | Triclinic | 1.532-1.542 | 0.01 | Weak | Dark brown-red |
Axinite | 6.5+ | 3.27-3.29 | Triclinic | 1.675-1.685 | -0.01 | Strong | None |
Azurite | 3.5+ | 3.7-3.9 | Monoclinic | 1.730-1.838 | 0.108 | Definite | None |
Barite Barytes | 3 | 4.5 | Orthorhombic | ||||
Barytocalcite | 4 | 3.66 | Monoclinic | ||||
Benitoite | 6+ | 3.65-3.68 | Triagonal | 1.757-1.804 | 0.047 | v Strong | Strong blue |
Beryl | 7.5+ | 2.65-2.75 | Hexagonal | 1.570-1.600 | -0.006 -0.009 | Definite to weak | Weak to none |
Beryllonite | 5.5+ | 2.80-2.85 | Monoclinic | 1.553-1.562 | -0.009 | None | None |
Brazilianite | 5.5 | 2.98-2.99 | Monoclinic | 1.603-1.623 | 0.02 | v Weak | None |
Bytownite | 6 | 2.71-2.74 | |||||
Calcite | 3 | 2.71 | Hexagonal | ||||
Cancrinite | 5 to 6 | 2.4-2.5 | |||||
Cassiterite | 6 to 7 | 6.8-7.1 | Tetragonal | 1.997-2.093 | 0.096 | Definite | None |
Celestine Celestite | 3+ | 3.97-4.00 | Orthorhombic | ||||
Cerussite | 3.5 | 6.46-6.57 | Orthorhombic | 1.804-2.078 | -0.274 | None | Variable to None |
Chalcedony (Quartz) | 6.5+ | 2.58-2.64 | Hexagonal | 1.544-1.553 | upto+0.006 | None | Blue-white |
Chalcopyrite Copperpyrite | 3.5+ | 4.1-4.3 | Tetragonal | ||||
Chalybite Siderite | 3.5 to 4.5 | 3.85 | Hexagonal | ||||
Chloromelanite Jade | 6.5+ | 3.30-3.36 | Monoclinic | 1.654-1.667 | +0.013toNone | None | v Weak |
Chromite | 5.5 | 4.10-4.90 | |||||
Chrysoberyl | 8.5 | 3.70-3.72 | Orthorhombic | 1.744-1.755 | 0.011 | v Weak | None |
Chrysocolla | 2 to 5.5 | 2.00-2.40 | Amorphous | About1.50 | None | Weak | None |
Chrysoprase (Quartz) | 6.5+ | 2.58-2.64 | Hexagonal | 1.544-1.553 | up to +0.004 | v Weak | None |
Citrine Quartz | 7 | 2.65 | Hexagonal | 1.544-1.553 | 0.009 | v Weak | None |
Colemanite | 4.5 | 2.42 | Monoclinic | ||||
Coral | 3 to 4 | 2.6-2.7 | hexagonal | 1.486-1.658 | -0.172 | None | Weak |
Cordierite | 7+ | 2.58-2.66 | Orthorhombic | 1.53-1.55 | -0.008-0.012 | v Strong | None |
Crocoite | 2.5+ | 5.9-6.1 | Monoclinic | ||||
Cuprite | 3.5+ | 5.85-6.15 | Isometric | ||||
Danburite | 7+ | 3 | Orthorhombic | 1.630-1.636 | -0.006 | Weak | Sky Blue |
Datolite | 5+ | 2.90-5.00 | Monoclinic | ||||
Dematoid Garnet | 6.5+ | 3.62-3.85 | Isometric | 1.888-1.889 | None | None | None |
Diamond | 10 | 3.47-3.55 | Isometric | 2.417-2.419 | None | None | Variable |
Diopside | 5 to 6 | 3.27-3.31 | Monoclinic | 1.671-1.726 | 0.028 | Weak | Strong dark violet |
Dioptase | 5 | 3.28-3.35 | Hexagonal | 1.664-1.709 | 0.053 | Weak | None |
Dolomite | 3.5 to 4.5 | 2.85-2.95 | Hexagonal | ||||
Dumortierite | 7 | 3.26-3.41 | orthorhombic | 1.686-1.723 | -0.037 | Strong | Weak |
Ekanite | 6+ | 3.28 | |||||
Elaeolite | 5.5+ | 2.55-2.65 | |||||
Emerald | 7.5+ | 2.67-2.78 | Hexagonal | 1.576-1.582 | 0.006 | Definite | None |
Enstatite | 5.5 | 3.26-3.28 | Orthorhombic | 1.663-1.673 | 0.01 | Definite | None |
Epidot | 6 to 7 | 3.4 | Monoclinic | 1.733-1.768 | 0.035 | Strong | None |
Euclase | 7.5 | 3.1 | Monoclinic | 1.652-1.672 | 0.02 | v Weak | None |
Fluorite | 4+ | 3.18 | Isometric | 1.434 | None | None | Usually strong blue-violet |
Fossilized Wood (Quartz) | 6.5+ | 2.60-2.65 | Hexagonal | About1.54 | None | None | None |
Gahnite | 7.5+ | 3.58-3.98 | |||||
Garnet | 7+ | 3.60-3.80 | Isometric | 1.730-1.815 | None | None | None |
Garnierite | 2.5+ | 2.3-2.8 | (Organic) | ||||
Gaylussite | 2.5 | 1.99 | Monoclinic | ||||
Glass* | 5 | 3.15-4.20 | Amorphous | About1.50 | None | None | Variable |
Grossular Garnet | 7+ | 3.60-3.68 | Isometric | 1.738-1.745 | None | None | None |
Hambergite | 7.5 | 2.35 | Orthorhombic | 1.559-1.631 | 0.072 | None | None |
Hauynite | 5.5+ | 2.4 | Isometric | ||||
Heliotrope Bloodstone (Quartz) | 6.5+ | 2.6-2.7 | Hexagonal | 1.54-1.55 | up to +0.006 | None | Variable |
Hematite | 5.5 to 6.5 | 4.95-5.16 | Hexagonal | 2.94-3.22 | -0.28 | None | None |
Hemimorphite | 5 | 3.4-3.5 | Orhtorhombic | 1.614-1.636 | 0.022 | None | Weak to None |
Hiddenite Spodumene | 6 to 7 | 3.16-3.20 | Monoclinic | 1.665-1.680 | 0.015 | Definite | v Weak |
Howlite | 3.5 | 2.53-2.59 | Monoclinic | ||||
Hypersthene | 5 to 6 | 3.4-3.5 | Orthorhombic | ||||
Idocrase | 6.5 | 3.32-3.42 | Tetragonal | 1.700-1.721 | +-0.005 | Weak | None |
Ilmenite | 5 to 6 | 4.72 | |||||
Iolite | 7+ | 2.58-2.66 | Orthorhombic | 1.53-1.55 | -0.008-0.012 | v Strong | None |
Ivory | 2 to 4 | 1.7-2.0 | (Organic) | 1.54 | None | None | Various blues |
Jadeite Jade | 6.5+ | 3.35 | Monoclinic | 1.654-1.667 | +0.013 to None | None | v Weak |
Jasper Quartz | 6.5+ | 2.58-2.91 | Hexagonal | About1.54 | None | None | None |
Jet | 2.5 to 4 | 1.30-1.35 | 1.64-1.68 | None | None | None | |
Kornerupine | 6.5+ | 3.27-3.31 | Orthorhombic | 1.665-1.682 | -0.013 | Strong | None |
Kunzite Spodumene | 6 to 7 | 3.16-3.20 | Monoclinic | 1.665-1.680 | 0.015 | Definite | Strong |
Kurnakovite | 4.5 | 1.86 | Triclinic | ||||
Kyanite | 4.5 to 7 | 3.65-3.69 | Triclinic | 1.715-1.732 | -0.017 | Strong blues to colorless | Strong red |
Labradorite | 6+ | 2.69-2.70 | Triclinic | 1.560-1.568 | 0.008 | None | Yellow striations |
Lapis Lazuli | 5 to 6 | 2.4-2.9 | Isometric | About 1.50 | None | None | Strong white |
Lazulite | 5 to 6 | 3.1-3.2 | Monoclinic | 1.615-1.673 | -0.03 | Strong | None |
Leucite | 5.5 | 2.45-2.50 | Isometricand Tetragonal | ||||
Magnesite | 4 | 3.0-3.12 | |||||
Malachite | 3.5+ | 3.75-3.95 | Monoclinic | 1.655-1.909 | -0.254 | v Strong | None |
Meerschaum | 2+ | 2 | Orthorhombic Microcrystaline | 1.53 | None | None | None |
Moissanite* | 9.5 | 3.2 | Yes | ||||
Moldavite (tektite) | 5.5 | 2.32-2.38 | Amorphous | 1.48-1.50 | None | None | None |
Moonstone | 6+ | 2.56-2.62 | Monoclinic | 1.520-1.525 | -0.005 | None | Weak |
Natrolite | 5.5 | 2.20-2.25 | Orthorhombic | ||||
Nephrite Jade | 6+ | 2.90-3.02 | Monoclinic | 1.600-1.627 | -0.027 to none | Weak | None |
Obsidian (Naturalglass) | 5+ | 2.3-2.8 | Amorphous | 1.48-1.51 | None | None | None |
Opal | 5.5 to 6.5 | 1.98-2.20 | Amorphous | 1.44-1.46 | None | None | Variable |
Orthoclase | 6+ | 2.56-2.60 | Monoclinic | 1.520-1.525 | -0.005 | None | Weak |
Painite | 7.5+ | 4.1 | |||||
Pearl | 3 to 4 | 2.60-2.78 | Microcrystaline | 1.52-1.69 | Weak or none | None | Weak |
Periclase | 5.5+ | 3.70-3.90 | Isometric | ||||
Peridot | 6.5+ | 3.27-3.36 | Orthorhombic | 1.654-1.690 | 0.036 | v Weak | None |
Petalite | 6+ | 2.4 | Monoclinic | 1.502-1.518 | 0.016 | None | Weak orange |
Phosgenite | 2.5+ | 6.13 | Tetragonal | ||||
Prasiolite** (Quartz) | 7 | 2.65 | Hexagonal | 1.544-1.553 | 0.009 | v Weak | None |
Prehnite | 6+ | 2.87-2.93 | Orthorhombic | 1.61-1.64 | 0.03 | None | None |
Proustite Rubysilver | 2.5 | 5.57-5.64 | Tetragonal | ||||
Pseudophite | 2.5 | 2.5-2.6 | |||||
Psilomelane | 5.5+ | 4.35 | |||||
Purpurite | 4.5 | 3.2-3.4 | Orthorhombic | ||||
Pyrite | 6+ | 5.0-5.2 | Isometric | Over1.81 | None | None | None |
Pyrope Garnet | 7+ | 3.65-3.80 | Isometric | 1.730-1.760 | None | None | None |
Rhodochrosite | 4 | 3.30-3.70 | Hexagonal | 1.600-1.820 | -0.22 | None | Weak red |
Rhodolite (PyropeGarnet) | 7+ | 3.65-3.80 | Isometric | 1.730-1.760 | None | None | None |
Rhodonite | 5.5 to 6.5 | 3.40-3.70 | Triclinic | 1.733-1.744 | 0.011 | Definite | None |
Rhodozite | 8 | 3.4 | |||||
Rock-Crystal (Quartz) | 7 | 2.65 | Hexagonal | 1.544-1.553 | 0.009 | v Weak | None |
Rose Quartz | 7 | 2.65 | Hexagonal | 1.544-1.553 | 0.009 | Weak | Weak |
Ruby Corundum | 9 | 3.97-4.08 | Hexagonal | 1.766-1.774 | -0.008 | Strong | Strong red |
Rutile | 6+ | 4.20-4.30 | Tetragonal | ||||
Sanidine | 6 | 2.57-2.58 | |||||
Sapphire Corundum | 9 | 3.99-4.00 | Hexagonal | 1.766-1.774 | -0.008 | Varies | Variable |
SardQuartz | 6.5+ | 2.58-2.64 | Hexagonal | 1.544-1.553 | up to +0.006 | None | None |
Scapolite | 5 to 6.5 | 2.57-2.74 | Tetragonal | 1.540-1.560 | -0.009 -0.020 | Definite | Variable |
Scheelite | 4.5+ | 5.1-6.1 | Tetragonal | 1.918-1.934 | 0.016 | Definite | Variable |
Serpentine | 2.5 | 2.4-2.8 | Monoclinic | 1.560-1.571 | None | None | Partly yellow |
Sillimanite | 6 to 7.5 | 3.25 | |||||
Sinhalite | 6.5 | 3.47-3.49 | Orthorhombic | 1.669-1.707 | -0.038 | Definite | None |
Smaragdite | 6.5 | 3.25 | Monoclinic | ||||
Smithsonite | 5 | 4.3-4.5 | Hexagonal | 1.621-1.849 | -0.228 | None | None |
SmokyQuartz | 7 | 2.65 | Hexagonal | 1.544-1.553 | 0.009 | Definite | None |
Sodalite | 5.5+ | 2.13-2.29 | Isometric | 1.48 | None | None | Strong orange |
Spessartite (Garnet) | 7+ | 4.12-4.20 | Isometric | 1.795-1.815 | None | None | None |
Sphalerite | 3.5+ | 4.08-4.10 | Cubic | 2.368-2.371 | None | None | Variable to None |
Sphene | 5+ | 3.52-5.54 | Monoclinic | 1.885-2.050 | +0.105 +0.135 | Variable | None |
Spinel | 8 | 3.58-3.61 | Isometric | 1.712-1.736 | None | None | Strong red Weak other colors |
Staurolite | 7+ | 3.7-3.8 | |||||
Stichtite | 1.5 to 2.5 | 2.2 | Monoclinic | 1.560-1.571 | None | None | |
Strontiumtitanite* | 6+ | 5.13 | |||||
Sulphur | 1.5+ | 2.05-2.08 | Orthorhombic | ||||
Taaffeite | 8 | 3.6 | |||||
Tantalite | 5 to 6 | 5.18-8.20 | Orthorhombic | ||||
Tanzanite | 6.5+ | 3.28-3.35 | Orthorhombic | 1.691-1.700 | 0.009 | v Strong | None |
Thomsonite | 5+ | 2.3-2.4 | |||||
Thulite | 6 | 3.35 | Orthorhombic | 1.691-1.700 | 0.009 | None | None |
Tiger's Eye (Quartz) | 7 | 2.64-2.71 | Hexagonal | 1.544-1.553 | 0.009 | None | None |
Topaz | 8 | 3.53-3.56 | Orthorhombic | 1.610-1.638 | +0.008 -0.010 | Definite to weak | Weak |
Tourmaline | 7+ | 3.02-3.26 | Hexagonal | 1.616-1.652 | -0.014 -0.044 | Definite to strong | Weak |
Tremolite | 5.5 to 6.5 | 2.90-3.10 | |||||
Tugtipite | 6 | 2.36-2.57 | Tetragonal | Strong red | |||
Turquoise | 5 to 6 | 2.60-2.80 | Triclinic | 1.61-1.65 | 0.04 | Weak | Weak |
Ulexite | 2 | 1.9-2.0 | Triclinic | 1.491-1.520 | 0.029 | None | variable |
Uvarovite Garnet | 7.5 | 3.77 | Isometric | 1.87 | None | None | None |
Variscite | 4 to 5 | 2.4-2.6 | Orthorhombic | 1.55-1.59 | -0.01 | None | None |
Vivianite | 1.5 to 3 | 2.6-2.7 | Monoclinic | ||||
Wardite | 5 | 2.81 | |||||
Willemite | 5.5 | 3.89-4.18 | Tetragonal | Strong green | |||
Witherite | 3.5 | 4.27-4.35 | Orthorhombic | ||||
Wulfenite | 3 | 6.7-7.0 | Tetragonal | ||||
YAG* | 8 | 4.6 | |||||
Zincite | 4.5+ | 5.66 | Hexagonal | ||||
Zircon | 6.5 to 7.5 | 4.90-4.71 | Tetragonal | 1.777-1.987 | 0.059 | v WeaktoDefinite | Weak |
Zoisite | 6.5+ | 3.28-3.35 | Orthorhombic | 1.691-1.700 | 0.009 | v Strong | None |
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